A battery backup unit may replace the uninterruptible power supply (UPS). Under the circumstances when abnormality (such as power off, power insufficient, power interference or surge) occurs to a main power supplied to a rack server system, the battery backup unit supplies power to the rack server system to maintain normal operation; and a power supply apparatus such as a power generator is activated to provide backup power. In general, the battery backup unit is used for maintaining necessary operations for critical commercial or precision apparatuses, such as rack server systems, switches, to prevent data loss lest the business might suffer from tremendous loss or other unexpected consequences.
Validity of the battery backup unit has much to do with system stability. If the battery backup unit fails due to aging or other factors, the battery backup unit may not maintain the normal operation of the rack server system when abnormality occurs to the main power supplied to the rack server system, and data may be lost. To assure the validity of the battery backup unit, validity test such as discharge test is performed on the battery backup unit periodically to obtain whether the battery has sufficient power.
However, if abnormity, such as power off, occurs to the main power supplied to the rack server system when the battery backup unit is in discharge test, power stored in the battery backup unit may be nearly used up and the battery backup unit may be unable to maintain the normal operation of the rack server system. Meanwhile, the rack server system may have stability problem which may lead to data loss. Therefore, how to reduce the risk of data loss of the rack server system has become a prominent task for the industries.